While mobile electrical machines and especially electric vehicles having rechargeable energy-storage means such as batteries, are known, there have not been provided heretofore to our knowledge, any means for determining the effective work done by such vehicles or for accounting for the energy consumption thereof. Such vehicles are, of course, generally recharged from an electrical supply network and hence all accounting for the electric power supplied has hitherto been in the nature of measurement of the power supplied by the vehicle-owner's network to his own vehicles.
With automotive vehicle powered by other means, e.g. gasoline or diesel fuel, there exist service stations distributed throughout a region at which a vehicle can be refilled with the energy medium, namely, the fuel. At such stations, the fuel metered into the vehicle is determined and an immediate accounting is provided whereby the fuel consumed is charged to the user.
With increasing usage of electric motor vehicles, there is a need for an infrastructure of supply stations at which the vehicles can be recharged, i.e. supplied with electrical energy which is stored by, for example, the electrochemical means described previously. Until now, to our knowledge, there has been no practical way in which this could be achieved at a plurality of electrical-supply service stations so that a fair accounting for the electrical consumption of and other charges for operating the vehicle could be made.